Abstract: AIM: To observe the effect pre-injection of Dexmedetomidine on safety during Etomidate induction of general anesthesia.METHODS: Eighty patients with ASA I-Ⅱ scheduled for head or neck surgery were randomly assigned to 4 groups:A(n=20),B(n=20),C(n=20),D(n=20).Group A,B received Dexmedetomidine 1 μg/kg intravenous injection and the whole dose was given within 10 minutes.Group C,D received equal volume of normal saline as Group A intravenously without Dex. Anesthesia was induced with Sufentanil 0.5 μg/kg,Atracurium 0.6 mg/kg and Etomidate 0.2 mg/kg in group A,C .Anesthesia was induced with propofol 1.5 mg/kg in group B,D.All other induction and maintenance drugs were same for two groups.HR,SBP,DBP,BIS were recorded at the time points of pre-administration of Dexmedetomidine (T₀,base value),l min after administration(T₁),10 min after administration(T₂),pre-intubation(T₃),intubation(T₄),l min after intubation(T₅),3 min after intubation(T₆),10 min after intubation(T₇).SpO₂, Ramesay scale were recorded at the time points of T₀ and T₂.RESULTS: After Dexmedetomidine was given,SpO₂ decreased (P<0.01) and Ramesay scale increased in group A and group B(P<0.01).There was no obvious change in group C,D(P>0.05). Compared with the base value,SBP and DBP of each group was decreased at T₃ (P<0.05); compared with the base value,SBP,DBP,and HR of Group C increased obviously with intubation (P<0.05),and HR remained higher than group A and group B after intubation(P<0.01);Compared with the group C,SBP,DBP,and HR of group A and group B were lower at T₄ and T₅(P<0.05).Compared with the group B,SBP and NBP of group A were higher at T₄ (P<0.05). SBP,DBP,and HR at T₅-T₇ were not signficantly different between group A and group B(P>0.05). Compared with the base value,BIS of group A and group B were decreased at T₂ (P<0.01), BIS of group A,B,D were lower than group C at T₅ (P<0.05).CONCLUSION: A single dose of Dexmedetomidine can effectively reduce cardiovascular responses to tracheal intubation during induction of general anaesthesia. Etomidate remain better instantaneous cardiovascular response to laryngoscope and intubation than Propofol and is similar with Propofol in inhibiting the stress response after tracheal intubation during general anaesthesia.

Key words: Dexmedetomidine, Propofol, Etomidate, Tracheal intubation, Hemodynamic